bevy/examples/3d/split_screen.rs
Aceeri ddfafab971 Windows as Entities (#5589)
# Objective

Fix https://github.com/bevyengine/bevy/issues/4530

- Make it easier to open/close/modify windows by setting them up as `Entity`s with a `Window` component.
- Make multiple windows very simple to set up. (just add a `Window` component to an entity and it should open)

## Solution

- Move all properties of window descriptor to ~components~ a component.
- Replace `WindowId` with `Entity`.
- ~Use change detection for components to update backend rather than events/commands. (The `CursorMoved`/`WindowResized`/... events are kept for user convenience.~
  Check each field individually to see what we need to update, events are still kept for user convenience.

---

## Changelog

- `WindowDescriptor` renamed to `Window`.
    - Width/height consolidated into a `WindowResolution` component.
    - Requesting maximization/minimization is done on the [`Window::state`] field.
- `WindowId` is now `Entity`.

## Migration Guide

- Replace `WindowDescriptor` with `Window`.
    - Change `width` and `height` fields in a `WindowResolution`, either by doing
      ```rust
      WindowResolution::new(width, height) // Explicitly
      // or using From<_> for tuples for convenience
      (1920., 1080.).into()
      ```
- Replace any `WindowCommand` code to just modify the `Window`'s fields directly  and creating/closing windows is now by spawning/despawning an entity with a `Window` component like so:
  ```rust
  let window = commands.spawn(Window { ... }).id(); // open window
  commands.entity(window).despawn(); // close window
  ```

## Unresolved
- ~How do we tell when a window is minimized by a user?~
  ~Currently using the `Resize(0, 0)` as an indicator of minimization.~
  No longer attempting to tell given how finnicky this was across platforms, now the user can only request that a window be maximized/minimized.
  
 ## Future work
 - Move `exit_on_close` functionality out from windowing and into app(?)
 - https://github.com/bevyengine/bevy/issues/5621
 - https://github.com/bevyengine/bevy/issues/7099
 - https://github.com/bevyengine/bevy/issues/7098


Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2023-01-19 00:38:28 +00:00

113 lines
3.5 KiB
Rust

//! Renders two cameras to the same window to accomplish "split screen".
use std::f32::consts::PI;
use bevy::{
core_pipeline::clear_color::ClearColorConfig, prelude::*, render::camera::Viewport,
window::WindowResized,
};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_startup_system(setup)
.add_system(set_camera_viewports)
.run();
}
/// set up a simple 3D scene
fn setup(
mut commands: Commands,
asset_server: Res<AssetServer>,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
) {
// plane
commands.spawn(PbrBundle {
mesh: meshes.add(Mesh::from(shape::Plane { size: 100.0 })),
material: materials.add(Color::rgb(0.3, 0.5, 0.3).into()),
..default()
});
commands.spawn(SceneBundle {
scene: asset_server.load("models/animated/Fox.glb#Scene0"),
..default()
});
// Light
commands.spawn(DirectionalLightBundle {
transform: Transform::from_rotation(Quat::from_euler(EulerRot::ZYX, 0.0, 1.0, -PI / 4.)),
directional_light: DirectionalLight {
shadows_enabled: true,
..default()
},
..default()
});
// Left Camera
commands.spawn((
Camera3dBundle {
transform: Transform::from_xyz(0.0, 200.0, -100.0).looking_at(Vec3::ZERO, Vec3::Y),
..default()
},
LeftCamera,
));
// Right Camera
commands.spawn((
Camera3dBundle {
transform: Transform::from_xyz(100.0, 100., 150.0).looking_at(Vec3::ZERO, Vec3::Y),
camera: Camera {
// Renders the right camera after the left camera, which has a default priority of 0
order: 1,
..default()
},
camera_3d: Camera3d {
// don't clear on the second camera because the first camera already cleared the window
clear_color: ClearColorConfig::None,
..default()
},
..default()
},
RightCamera,
));
}
#[derive(Component)]
struct LeftCamera;
#[derive(Component)]
struct RightCamera;
fn set_camera_viewports(
windows: Query<&Window>,
mut resize_events: EventReader<WindowResized>,
mut left_camera: Query<&mut Camera, (With<LeftCamera>, Without<RightCamera>)>,
mut right_camera: Query<&mut Camera, With<RightCamera>>,
) {
// We need to dynamically resize the camera's viewports whenever the window size changes
// so then each camera always takes up half the screen.
// A resize_event is sent when the window is first created, allowing us to reuse this system for initial setup.
for resize_event in resize_events.iter() {
let window = windows.get(resize_event.window).unwrap();
let mut left_camera = left_camera.single_mut();
left_camera.viewport = Some(Viewport {
physical_position: UVec2::new(0, 0),
physical_size: UVec2::new(
window.resolution.physical_width() / 2,
window.resolution.physical_height(),
),
..default()
});
let mut right_camera = right_camera.single_mut();
right_camera.viewport = Some(Viewport {
physical_position: UVec2::new(window.resolution.physical_width() / 2, 0),
physical_size: UVec2::new(
window.resolution.physical_width() / 2,
window.resolution.physical_height(),
),
..default()
});
}
}